1. Field of the Invention
The invention relates to network communication technology, and particularly, to a method for resource reservation in customer request mode in Next Generation Network, and a Next Generation Network (NGN) Resource and Admission Control System (RACS) supporting resource reservation in customer request mode, and a Resource Mediation Policy Decision Function (RM-PDF) thereof.
2. Background of the Invention
In an NGN, packet technologies, such as Internet Protocol (IP) packet, are adopted as bearer network technologies to integrate fixed communication and mobile communication. So an NGN is an integrated network which bears multiple telecommunication services including voice, graphic and data services through IP connectivity among communication entities. Though the NGN has already been brought into the phase of deployment, perfect solutions are still expected to solve the problems in Quality of Service (QoS), security, reliability, operability and manageability in networks over IP.
Two international standard organizations, International Telecommunication Union (ITU-T) and European Telecommunication Standard Institute (ETSI) have established research teams to work on NGN standards. Currently they are working on the frameworks of the NGN. However, it has been a common understanding of the most mainstream operators and equipment providers that an RACS should be adopted to solve the problems concerning QoS, network address translation (NAT) and firewall traversal in an NGN bearer network.
Although the RACS drafts of the two organizations cover different scopes, i.e. the ITU-T Focus Group on Next Generation Networks (FGNGN) takes core network packet transport as well as access network packet transport into consideration, the frameworks produced by the two organizations are similar and compatible with each other. Both organizations have adopted the idea of admission control at network edges according to operation policy rules in the 3GPP policy decision function (PDF) and PacketCable Gate Controller (GC); they have both added network internal resource availability check result as one of admission control criteria to avoid unacceptable congestion, delay or packet loss in application layer. The unacceptable congestion, delay or packet loss result from the level requirements of the traffic flow and service quality exceeding the network bearer capabilities; they have both enhanced NAT and firewall traversal control and they have both taken the support to various NGN multimedia services into consideration.
Currently the framework definitions in RACS drafts are basically fixed and the RACS function framework needs to support multiple resource reservation modes. There are three major resource reservation modes currently.
(1) Proxy Request Mode
A piece of service control equipment initiates a resource request to the resource and admission control layer on behalf of a customer; the piece of service control equipment extracts the bandwidth and service level requirements of the session media stream specified from a customer service request signaling, or determines the bandwidth and service level requirements of a session media stream according to service layer operation policy rules (such as service type and coding/decoding type etc.).
(2) Customer Request Mode
A piece of customer premise equipment (CPE) directly initiates a resource request to a network through dedicated path coupled signaling; the resource request can be initiated it connection with a session or be independent of the session; the resource request may be authorized or unauthorized by a piece of service control equipment in advance.
(3) Access Configuration Mode
A piece of network access management equipment initiates a resource request to a network according to the customer service level agreement information in a customer configuration file when the customer accesses the network; the resource request is at the customer level and independent of the session.
In the latest RACS draft released by ITU-T FGNGN in December 2004, an RACS function framework architecture was provided, as shown in FIG. 1. The RACS function framework architecture includes the following functions.
Application Functions (AF), which are service layer functions used for requesting resource reservation and release from the resource and admission control system for an application media stream, for example a service control proxy function (SCPF) and an interconnection border control function (IBCF).
Network Access Attachment Function (NAAF), which includes functions related to network access management control, and is in charge of network access authentication, authorization and dynamic IP address allocation for customer equipment, access equipment configuration and storage of the customer configuration file, etc.
Resource Mediation (RM) functions, which receive resource reservation requests, determines whether a resource reservation request complies with operation policy rules, and interact with related functions to determine whether a resource reservation request complies with the customer configuration information stored in a customer configuration database and whether there is idle transport resource available which meets the requirements in the network, and make admission decision according to determination results; the resource mediator functions include a mediation policy decision function (M-PDF) on the service access side and an interconnection policy decision function (I-PDF) on the service interconnection side.
Transport Resource Control Functions (TRCF), which receive a resource request from resource mediators, determine whether there is idle transport resource available that meets the requirements of the resource request in the network according to the network topology and resource state data collected and maintained, and control QoS guarantee related forward action of transport equipment in the network; when there are multiple TRCF in a network, the multiple TRCF communicate with each other to check the resource availability of the whole network from the entrance edge to the exit edge; the TRCF includes an Access-Transport Resource Control Function (A-TRCF) in the access network and a Core-Transport Resource Control Function (C-TRCF) in the core network.
Border Gateway Function (BGF) in core network, which receives, stores and enforces admission decision parameters from resource and admission control layer, and further performs message filtering, traffic classification, labeling, monitoring and trimming according to the parameters, and, possibly performs network address conversion and security check filtering of messages.
In this draft, though the descriptions of functions and interface requirements are developed around proxy request mode, complete interface requirements and relevant workflows, used for reserving resources in proxy request mode, are not provided. Moreover, even though support to customer request mode is stated in the general requirements of the draft, technical solutions for resource reservation in customer request mode are provided in none of the chapters of functions, interface requirements and workflows.
In the latest RACS draft released by ETSI TISPAN in January 2005, an RACS function framework architecture is also provided, as shown in FIG. 2, the RACS function framework architecture includes the following functions.
AF, which are service layer functions used for requesting resource reservation and release from the resource and admission control system for an application media stream.
Network Attachment Subsystem (NASS), which is in charge of functions related to network access management control, such as network access authentication, authorization and dynamic IP address allocation for customer equipment, access equipment configuration and storage of the customer configuration file, etc.
Service Policy Decision Function (SPDF), which receives a resource reservation request, determines whether the resource reservation request complies with operation policy rules, interacts with A-RACF to determine whether there is idle transport resource available which meets the requirements in the network, and makes admission decision according to determination results.
A-RACF, which receives the resource request from the SPDF, determines whether there is idle transport resource available which meets the requirements in the network, and controls QoS guarantee related forward action of access transport equipment.
Core network Border Gateway Function (C-BGF), which receives, stores, and enforces admission decision parameters from resource and admission control layer, and further performs message filtering, traffic classification, labeling, monitoring and trimming according to the parameters, and yet possibly performs network address conversion and security check filter of messages.
In this draft, the descriptions of functions and interface requirements are also developed around proxy request mode. However, complete interface requirements and relevant workflows are not provided either. Therefore, no corresponding detailed solution is provided for resource reservation in customer request mode.